What kind of ant is this? (Uli, Brunei)

The ants pictured belong to the genus Cataulacus, a group of arboreal-nesting ants widely distributed across the Old World tropics. The exact species is likely Cataulacus latissimus, one of the more sizable of the dozen or so Indo-Australian species, known to occur in West Malaysia, Sumatra, Singapore, and of course Borneo.